1. Field of the Invention
This invention relates to a radiation-sensitive resin composition containing an alkali-soluble resin. More particularly, this invention relates to a radiation-sensitive resin composition preferable as a resist used for fabricating integrated circuits, that is well sensitive to a variety of radiations including ultraviolet radiation such as g-rays and i-rays, far-ultraviolet radiation such as KrF excimer laser radiation, X-radiation such as synchrotron radiation, and charged-particle radiation such as electron radiation, in particular, ultraviolet radiation and far-ultraviolet radiation.
2. Description of the Prior Art
As integrated circuits have become more highly integrated in recent years, positive resist compositions used when the integrated circuits are fabricated are required to have superior performances in respect of resolution, sensitivity, depth of focus (focal latitude), heat resistance, developability and so forth.
In the manufacture of ultra LSI circuits, besides the requirement for the above performances, there is a demand for resist compositions restrained from the standing-wave effect due to the interference of irradiation light with light reflected from the substrate.
As a method for restraining halation of positive resists, U.S. Pat. No. 5,334,481 (1994) discloses a positive photosensitive composition containing as a light-absorbing dye a phenol compound represented by the following formula (2): ##STR2## wherein R.sup.1 to R.sup.4 each represent a hydroxyl group or an alkoxyl group having 1 to 6 carbon atoms, and R.sup.5 to R.sup.10 each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Japanese Post-examination Patent Publication (kokoku) No. 6-58530 also discloses a positive photosensitive composition containing novolak resin, benzophenone and 1,2-napthoquinonediazidosulfonic acid ester of curcumine.
However, even the above positive photosensitive compositions can not be satisfactory in the performances such as resolution, sensitivity, heat resistance and developability.
As a means for restraining the standing-wave effect, a technique to add a light-absorbing dye is added in resists has been developed. The light-absorbing dye, however, has caused the problem that a lowering of sensitivity, a shape deterioration of resist patterns and a poor dimensional stability concurrently thereby caused make it difficult to deal with the formation of fine patterns. In addition, there are problems that some light-absorbing dyes do not dissolve in solvents, may cause deposition of fine particles during storage, and may sublimate at the time of baking to make resist performances non-uniform.